In this paper, we define a resolution method to study the effect of a porous material on vibro-acoustic behavior of a geared transmission. A porous plate is coupled with the gearbox housing cover. The developed model depends on the gearbox characteristic and poroelastic parameters of the porous material. To study the acoustic effect of the housing cover, the acoustic transmission loss is computed by simulating numerically the elastic-porous coupled plate model, and the numerical implementation is performed by directly programming the mixed displacement-pressure formulation. To study the vibration effect, the bearing displacement is computed using a two-stage gear system dynamical model and used as the gearbox cover excitation. Numerical implementation is performed by direct programming of the Leclaire formulation.